On an aircraft wing, a trailing edge flap is typically mounted so as to be movable between a retracted position and one or more extended positions for increasing the maximum lift coefficient of the wing. The flap deployment typically comprises a downward deflection, which may be effected by a downward rotary movement and/or a movement in the aft/downward direction with respect to the fixed wing.
A spoiler is a lift dumping device typically provided on the upper aerodynamic surface of the wing between the fixed wing and the trailing edge flap so as to overlay the flap when they are both in their respective retracted positions. The spoiler typically moves between a retracted (0 degree) cruise position and an upwardly extended (positive rotation angle) lift dump position. A so-called droop spoiler can also be moved to a downwardly extended (negative rotation angle) position when the flap is partially or fully deployed for take-off and landing configurations, so as to manage the gap between the spoiler and the flap. Managing this gap can significantly improve the aerodynamic performance of the wing in a high lift configuration.
It is generally desirable that the lateral extent of each set of flaps and spoilers (inboard and outboard) is approximately coincident in the wing spanwise direction. However this is not always achievable in practice, often due to packaging constraints.
Drooping spoilers may suffer particularly from packaging constraints since the drooped spoiler partially occupies the position vacated by the deployed flap, which may require that the lateral extent of the spoiler is cut back from the lateral extent of the flap to avoid a clash between the spoiler in its drooped position and the flap support/drive mechanism.
A variable camber wing is a wing that allows relatively small changes in the camber of the aerofoil profile. The trailing edge flaps and spoilers may form part of a variable camber wing system whereby the flaps and spoilers may deflect through relatively small angles (up to around plus/minus 3 degrees) from their nominal cruise retracted (0 degree) position.
Depending on the flap and spoiler configuration and their intended deployment it may be necessary to cut back the fixed wing structure to avoid clashing with the movement of the flight control surfaces. However any gaps which are opened up between the fixed wing structure and the flight control surfaces due to this cut back should also be managed to ensure aerodynamic performance is not degraded significantly, particularly during the cruise.